Page 50 - Index

2023 ‫מועד חורף‬ - 49 - ‫ פרק שני‬- ‫אנגלית‬

Text II (Questions 18-22)

(1) Crystals are found in many of the substances in the world around us – including the
minerals that make up rocks, compounds found in plants, and metals. Scientists have
long known that the molecules that make up crystalline substances are arranged in a
precise, three-dimensional geometric pattern that repeats itself. However, an exact

(5) map of a crystal's structure can be drawn only by using a technique called x-ray
diffraction crystallography.

When a beam of x-rays strikes a crystal, the crystal scatters the beam in many
different directions and with different intensities. By capturing a photographic image of
these scattered x-rays, one obtains a "diffraction pattern" that can be used in deciphering

(10) the molecular configuration of the crystal. Though no easy task, accurately determining
the crystal's structure is crucial to understanding its properties and behavior. Such
information can be extremely useful in many fields – for example, medicine.

A case in point is the research on insulin that was conducted by British scientist
Dorothy Crowfoot Hodgkin. Insulin is a hormone that regulates the body's processing

(15) of sugars and fats. Inadequate production or improper utilization of insulin results in
diabetes, a serious disease. In 1934, Hodgkin set out to ascertain the hormone's
molecular structure by using x-ray diffraction crystallography on samples of crystallized
insulin. At that time, x-ray diffraction crystallography was not sufficiently developed to
cope with the complexity of the insulin molecule, which consists of over 400 atoms.

(20) Over the years, Hodgkin, together with other researchers, radically improved x-ray
diffraction crystallography. She was awarded the Nobel Prize in Chemistry in 1964 for
her work. In 1969, after 35 years, she finally succeeded in resolving the molecular
structure of insulin.

Questions

18. The main purpose of the text is to -

(1) describe crystals and their molecular structure
(2) discuss an important scientific research method
(3) present a recent discovery in the field of medicine
(4) discuss Hodgkin's contribution to x-ray diffraction crystallography

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